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Sat Nov 08, 2025 7:25 pm

At some point before I bought my ‘63, someone moved the voltage regulator from under the seat and mounted it on the generator. I need to redo the wire connecting the voltage regulator to the starter/battery and can’t find the wire size printed on the wire.

Is it 10 or 8 ga?

Sat Nov 08, 2025 8:16 pm

If it's original wiring, it's metric, and won't be identified by AWG sizes.

Sat Nov 08, 2025 8:32 pm

A '63 is supposed to have the voltage regulator mounted on the generator, not under the back seat like later 12 volt Bugs.

If you want to duplicate the generator wiring setup used on 12 volt Bugs I would recommend copying the '67 wiring diagram. 6.0mm is best substituted with 8 gauge wire and 1.0mm is best substituted with 16 gauge wire (for both the wire will be slightly larger than original for a 12 volt generator car). It would likely be easier to convert the car to a 12 volt alternator with built in regulator.

Sat Nov 08, 2025 8:43 pm

Thanks for the info. I wasn’t aware that 63 had them installed on the generator. I was assuming this one was moved when the car was converted to 12v.

It’s nowhere near a restoration, so keeping is stock-ish isn’t an issue. I just didn’t want to burn up the wiring.

Thanks again.

Sun Nov 09, 2025 9:09 am

wires? they are just wires..

Sun Nov 09, 2025 10:15 am

EVfun wrote: A '63 is supposed to have the voltage regulator mounted on the generator, not under the back seat like later 12 volt Bugs.
Here's a page from the '63 Beetle Owners Manual showing the generator mounted VR:

Here's a real pic of a 40HP engine from the Engine Guide thread:

Sun Nov 09, 2025 11:48 am

runamoc wrote: wires? they are just wires..

I like that. It's a very handy chart. :idea:

I used to remind my people that the wire doesn't know or care what color it is

Sun Nov 09, 2025 12:35 pm

slayer61 wrote: runamoc wrote: wires? they are just wires..

I like that. It's a very handy chart. :idea:

I used to remind my people that the wire doesn't know or care what color it is

when I made my own wiring harness I used LEDS lights and a HSR, so I was able to use smaller than stock wire gauges. With this extra 'space' I ran 2 #10guage wires to the front. One connected to the lights switch. The other to #30 wire on the fuse panel.

it shows that 2 #12gauge wires can carry more current than one #8gauage, and 2 #10gauage wires can carry more current than one #6gauage wire. For some reason owners will spend more money on the bigger wire. :?

I'm in favor off point A to point B wire connections and hate 'in the middle' connections

Sun Nov 09, 2025 1:39 pm

runamoc wrote: when I made my own wiring harness I used LEDS lights and a HSR, so I was able to use smaller than stock wire gauges. With this extra 'space' I ran 2 #10guage wires to the front. One connected to the lights switch. The other to #30 wire on the fuse panel.

it shows that 2 #12gauge wires can carry more current than one #8gauage, and 2 #10gauage wires can carry more current than one #6gauage wire. For some reason owners will spend more money on the bigger wire. :?

I'm in favor off point A to point B wire connections and hate 'in the middle' connections

While two 12 gauge wires can carry more current than one 8 gauge wire the two 12 gauge wires will have slightly more voltage drop at the same total current. I wired my buggy in a similar fashion, with the fuse block by the battery and two 12 gauge wires running to the front, a yellow one going to the light switch and a red one going to the ignition switch.

I have my own little cheat sheet to determine wire size for automotive work. I notice that manufacturers often use even smaller wire sizes than this:

Code: AWG mm^2 mOhm/ft amps dia”
2 33.6 .156 100 .2576
4 21.2 .248 82 .2043
6 13.3 .395 65 .1620
8 8.37 .628 50 .1285
10 5.26 .999 36 .1019
12 3.31 1.59 25 .0808
14 2.08 2.53 16 .0641
16 1.31 4.02 10 .0508
18 .823 6.39 6 .0403
20 .518 10.2 3.5 .0320

Sun Nov 09, 2025 2:43 pm

runamoc wrote: slayer61 wrote: runamoc wrote: wires? they are just wires..

I like that. It's a very handy chart. :idea:

I used to remind my people that the wire doesn't know or care what color it is

when I made my own wiring harness I used LEDS lights and a HSR, so I was able to use smaller than stock wire gauges. With this extra 'space' I ran 2 #10guage wires to the front. One connected to the lights switch. The other to #30 wire on the fuse panel.

it shows that 2 #12gauge wires can carry more current than one #8gauage, and 2 #10gauage wires can carry more current than one #6gauage wire. For some reason owners will spend more money on the bigger wire. :?

I'm in favor off point A to point B wire connections and hate 'in the middle' connections

My line of work had minimum standards that "shall be" adhered to, and one of those minimums was the minimum size of parallel conductors. #12 did NOT meet the minimum. My line of work, did not include cars, however.

Sun Nov 09, 2025 2:46 pm

EVfun wrote: runamoc wrote: when I made my own wiring harness I used LEDS lights and a HSR, so I was able to use smaller than stock wire gauges. With this extra 'space' I ran 2 #10guage wires to the front. One connected to the lights switch. The other to #30 wire on the fuse panel.

it shows that 2 #12gauge wires can carry more current than one #8gauage, and 2 #10gauage wires can carry more current than one #6gauage wire. For some reason owners will spend more money on the bigger wire. :?

I'm in favor off point A to point B wire connections and hate 'in the middle' connections

While two 12 gauge wires can carry more current than one 8 gauge wire the two 12 gauge wires will have slightly more voltage drop at the same total current. I wired my buggy in a similar fashion, with the fuse block by the battery and two 12 gauge wires running to the front, a yellow one going to the light switch and a red one going to the ignition switch.

I have my own little cheat sheet to determine wire size for automotive work. I notice that manufacturers often use even smaller wire sizes than this:

Code: AWG mm^2 mOhm/ft amps dia”
2 33.6 .156 100 .2576
4 21.2 .248 82 .2043
6 13.3 .395 65 .1620
8 8.37 .628 50 .1285
10 5.26 .999 36 .1019
12 3.31 1.59 25 .0808
14 2.08 2.53 16 .0641
16 1.31 4.02 10 .0508
18 .823 6.39 6 .0403
20 .518 10.2 3.5 .0320

Yes. Manufacturers are held to a different standard than common folk. They normally have to satisfy the UL however

Sun Nov 09, 2025 3:48 pm

slayer61 wrote: Yes. Manufacturers are held to a different standard than common folk. They normally have to satisfy the UL however
I don’t think auto makers have to comply with UL listing. I’ve seen a wire between 16 gauge and 18 gauge (most likely 1.0mm) being used to ground both headlights through a stalk mounted light switch (Geo Metro). I had to fix the mess that resulted at about 100k miles. My Tacoma uses the same basic design and is known to have headlight issues (less often, so there must be a little more copper). Just the idea that all the lights are either powered or grounded through a tight bundle of wires running through steering column — they don’t seem to have heard about derating either.

Most of the time I’m more concerned about late fusing issues, over wire size issues, in homemade wiring solutions. Oh, and either color coding or wire labeling would really help when something doesn’t work. (Autos are big on color coding, UL is big on labeling.)

Sun Nov 09, 2025 6:47 pm

[quote="EVfun"] runamoc wrote:

While two 12 gauge wires can carry more current than one 8 gauge wire the two 12 gauge wires will have slightly more voltage drop at the same total current.

Code: AWG mm^2 mOhm/ft amps dia”
2 33.6 .156 100 .2576
4 21.2 .248 82 .2043
6 13.3 .395 65 .1620
8 8.37 .628 50 .1285
10 5.26 .999 36 .1019
12 3.31 1.59 25 .0808
14 2.08 2.53 16 .0641
16 1.31 4.02 10 .0508
18 .823 6.39 6 .0403
20 .518 10.2 3.5 .0320

went to this web-site and ran the numbers for 2 parallel #12 gauge copper conductors vs. single #8gauge copper conductor for voltage drop difference for 10 feet using 12volts. There is a .04 volts drop difference for the 2 #12gauge wires vs one #8guage wire. Yeah, slightly more voltage drop on the 2 wires. Not sure if my VOM is accurate enough to read that difference. 8)

https://www.calculator.net/voltage-drop-calculator...;ctype=nec

Sun Nov 09, 2025 7:30 pm

^^^ you do all this without a meter that reads millivolts?? ^^^

Much respect

Mon Nov 10, 2025 7:34 am

Quote: meter that reads millivolts?
never really had the need to measure millivolts on a VW electrical system. 8)

Mon Nov 10, 2025 8:44 am

runamoc wrote: Quote: meter that reads millivolts?
never really had the need to measure millivolts on a VW electrical system. 8)

I see. I used them regularly to check voltage drop across a shunt on an amp meter. Just different worlds.

Be well brother

Mon Nov 10, 2025 8:55 am

Quote: voltage drop across a shunt on an amp meter
doesn't the amp meter do that for you? 50mv=FullScale

Mon Nov 10, 2025 11:01 am

It does, if it's accurate and working. It was a double check on critical systems

Mon Nov 10, 2025 12:48 pm

Quote: if it's accurate
How? With another meter?

Mon Nov 10, 2025 3:07 pm

runamoc wrote: Quote: if it's accurate
How? With another meter?

Sure. The analog device lived out in the field exposed to the elements. The digital volt meter was kept stored in doors and was calibrated annually. The millivolt is also the output of a thermocouple, could be used to test voltage drop across a relay or motor starter on a DC circuit.

The power plants i worked in are quite regulated and overseen by NERC. The North American Electric Reliability Council.

Emphasis on RELIABILITY